Gear-changing device for motor vehicles



May 31, 1938. K. MAYBACH 2,113,978

I GEAR-CHANGING DEVICE FOR MOTOR VEHICLES Filed Dec, 4, 1935 5Sheets-Sheet 1 a Y 0 H I 4 a T; H 2 6 37 I MM 2 2930, We a:

May 31, 1938. MAYBACH GEAR-CHANGING DEVICE FOR MOTOR-VEHICLES Filed Dec.4, 1935 5 Sheets-Sheet 2 Inventor 1 May 31, 1938. K. MAYBACHGEAR-CHANGING DEVICE FOR MOTOR VEHICLES 5 Sheets-Sheet 3 Filed Dec. 4,1935 May 31, 1938. K. MAYBACH 2,118,978

GEAR-CHANGING DEVICE FOR MOTOR VEHICLES Filed Dec. 4, 1935 5 shets-sheet 4 lhmfar: 22 77776- y 1, 1938. K. MAYBACH 2,118,978

GEAR-CHANGING DEVICE FOR MOTOR VEHICLES Filed Dec. 4, 1935 5Sheets-Sheet 5 Patented May 31, 1938 UNITED STATES GEAR-CHANGING DEVICEFOR MOTOR VEHICLES Karl Maybach, Fricdrichshafen-on-the-Bodensee,Germany, assignor to Maybach-Motorenban G. in. Bodensee, Germany 11.,Friedrichshafen-on-the- Application December 4, 1935, Serial No. 52,919In Germany December 12, 1934 12 Claims. (01. 74-472) The inventionrelates to a gear-changing device for the change-speed gearing of motorvehicles (road motor vehicles and rail motor vehicles), whereby theoperation of gear-changing is simplified and to some extent is performedautomatically, and the safety of driving the vehicle is increased. .Alarge number of devices for the automatic gear-changing of change-speedgearing, more particularly in accordance with the engine speed arealready known. None of these automatic devices has become establishedbecause when the speed or torque which is decisive for the operation ofsucha device has been attained,

the automatic device also effects gear changes in cases in which suchgear changes are not desired by the driver.

Theinvention provides a gear-changing devicewhich operates automaticallyunder predetermined conditions but which may also be operatedoptionallyat any time by the driver. In the gear-changing device according to. theinvention, there is provided a gear-changing control member whichcontrols the supply of operating medium to the members effecting thechange of gear, for example the supply of pressure medium to cylinders,the pistons of which act upon the gear-changing rod. This. gear-changingcontrol member may on the one hand, be moved optionally by the driver intwo directions, that is to say for engaging a higher or lower gear. Onthe other hand, the control member according to the invention iscontrolled by a control means dependent upon the engine speed wherebyfor ex-' ample a pressure medium is controlled, after a maximum enginespeed has been reached, for the engagement of a higher gear. Thedeviceis, however, constructed so that this automatic control meanscannot effect a change from a higher gear to a lower gear. 011 thecontrary, the downward 40 gear-changing can be efiected always only bythe driver.

Cal

By means of the automatic device according to' the invention, ity ispossible at the same time to dispense with the governor customarilyprovided heretofore, for example in omnibuses and rail motor vehicles,for preventing the maximum engine speed from being exceeded. On'attaining 55 a centrifugal governor. Automatic gear-changing may therebyalso be influenced by the driver and adapted to the existing conditions.

The advantages of the automatic gear-changing device are moreparticularly felt when starting, for example in the case of city or townomnibuses which, due to the frequent halts, have always to be startingagain 'so that the driver is burdened with this work of gear-changingand his attention is diverted from the actual driving of the vehicle.

0n the other hand, the driver can at any time interrupt an automaticgear-changing sequence in operation as soon as he considers it desirableto have an-optional gear change. If the vehicle has'for example beenstarted and the device has 15 after the first gear, automaticallyengaged the second gear, the driver can engage by hand the fourth or astill higher gear directly, the third gear being passed over.

Furthermore, according to the invention it is 20 also possible by meansof the working medium,

.for example compressed air, actuating the gearchanging control member,to efiect the closing of the .carburettor throttle or the supply offuel, preferably towards the end of the adjusting move- 25 ment of-thegear-ch n g control member- The device for closing the carburettorthrottle may also be combined with a brake device acting upon the morerapidly rotatingwzlutch member. After changing gear, the actuation ofthe carburettor 30 throttle is immediately released again.

The automatic change of gear, to the next higher gear on exceeding themaximum engine speed, is efiected in the device according to. theinvention without the assistance of the driver. and 35 without influenceupon the setting of the accelerator which hasjust been made by thedriver.

If the driver has for example previouslyset the accelerator to fullsupply of combustible mixture,

the accelerator remains in this position, irrespece 40 tive of theregulation of the carburettor throttle by the automatic device.Gear-changing is effected exactly at thev right moment, that is, uponobtaining the maximum engine speedselected for the gear in question orthe vehicle speed c'orre- '45 sponding to the said engine speed.

. The driver is relieved of the work of gear changing, forexample onstarting, and may devote his whole attention tothe steering of thevehicle. Nevertheless, he can at any time change gear directly by handinthe sequence and speed which appear expedient to him. Above all,however, gear changing from a higher to a lower gearv is not effected bythe automaticallyoperating part of the device, but is leftentirely tothe a very low speed. He is thereby also not obhged to engagetheautomatic device again for the next, case of need, which would insomecases be done toolate.

The device according to the invention need,

only have a small weight and occupy a small amount of space, and itenables the usual clutch to be employed between the engine and changespeed gearing without modification, more particularly without theaddition of centrifugal weights- It also enables the necessary parts tobe manufactured in large quantities and'in unichange-speed gearinghaving clutches, iorexample. the known alternately en-' .gaged dogclutches, wherein the endiaces oi the form sizes for various types ofvehicles.

The action upon the regulating member of the carburettor may be effecteddirectly by the working medium controlled in accordance with the enginespeed, but in a further development of the invention, it is eiIected bythe fact that a control membenwhich is moved by the working mediumcontrolled in accordance withthe engine speedis held in itsgear-changing position until gear-changing has been effected.

In combination with the control 'member for changing gear in thechange-speed gearing, it is also possible to provide a device fordisengaging the clutch during the gear-changing operation. The deviceaccording to the invention will be employed with particular advantage,however, for

change-speed gearing in which a disengagement of the clutch is notnecessary, for example for over-running dogs are bevelled .so that uponthe application of the end races of the dogs against'each other prior tothe engagement, .the said. bevelled portions ca'us'ethe clutch membersto refuse each other until the previously more slowly running clutchmember begins to run more rapidly than the other clutch member. with theautomatic gear-changing device accord* ing to the invention,gear-changing is effected not only at the correct moment without theassistance oi the driver, the gear-changing operation being completed inthe shortest possible time,..but also without any shock or unpleasanteilect on the vehicle and itsoccupants, such as occur in the case ofother types of gearing andautomatic gear-changing devices. Alsocomplicated and expensive synchronizing devices are not necessary.

In such change-speed gearing with over-running clutches, known auxiliarydevices may be provided whereby, during the rejection period oi! thedogs, one of the clutch members is retarded or accelerated in order toattain the over-run- ,ning speed as quickly as possible- Preferably, insuch a case, a device operated by pressure medium will be employed. Suchdevices are described for example in the German patent specification No.569,392. The pressure medium-operative' in such a retarding device, mayalso be employed withspecial advantage in the device'according to theinvention for holding the control member, which is actuated by thepressure con? trolled in accordance with the engine speed, in theposition adJustedby'the said pressure until the gear-changing operationis completed. After ZLL completion or the gear-changing operation, theQressure 'supphed by the auxiliary device disap- In such gearing, incombination 'is actuated by a centrifugal governor I 2,118,978 driver,who will effect gear-changing not only The'optionaladjustment of thecarburettor by the driver may be eflected by the usual devices employingsuitable mechanical connections between such devices and thecorresponding parts of the device according to the invention, forexample a' lost motion connection may be provided in the rod gearconnected to the accelerator.

With special advantage however, thqadjiistment will likewise betransmitted by pressure medium from the adjusting member operated by thedriver to the device actuating the regulating member 01 the carburettor,inwhich case the control member actuated by the pressure in accordancewith the engine speed will be arranged in the conduit for the pressuremedium between the adjusting member and the actuating de'vice,

so that the admission of the pressure medium suppliedfrom the adjustingmember is prevented by the said control member so long as the automaticgear-changing device is in operation.

Two constructional examples of gear-changing devices according to theinvention are shown diagrammatically in the accompanying drawings.

Figure 1 shows'a first example with the operating parts mainly inection.

Figure 2 shows a section along the line A-A in Figure 1.

operating parts mainly in section.

' Figure 4 shows a section along the line 3-4;

v in Figure 3.

gear with gear-changing cylinders and control means.

Figure 7 shows by way of example a plan of an arrangement of the airpassages for controlling the gear changing cylinders.

Referring to Flgure 1', at l is shown a source of compressed air, 2 is,a conduit between the said source and the casing 3 oi! the control slidevalve 8 loaded by a spring ,4. The said valve 5 Figure 3 shows a secondexample with the comprises a passage 6'' and a longitudinal groove iopposite an aperture 6" in the casing 3 and The conduit 8 leads from thecasing 3 to a cylinder l, in which is situated a piston l'i loaded by aspring ll and having its piston rod 12 connected to a pawl i3 resting-ona stop pin I. At It is an aperture ior providing communication with theouter air, while It is a recess in the wall of the piston llcommunicating with 6. cylinder chamber by way of an orifice H. ii is aratchet wheel. I Theconduit i8 leads from the cylinder I to a cylinder10 containing a piston.

2|; having its piston rod 22- engaging a lever 23 'which is connected tothe throttle valve 25 provided inthe carburettor pipe 24 and is alsoengaged by a link 2!. .The disc 21, connected to the latter, isaccommodated in a casing 28 and is under the pressure oi a, spring 29.The

casing 28 is connected to a rod II which engages the accelerator 3|pulled by the spring 32 against the stop 83.

Figure 2 is a section Figure 1. v In this figure isa hand wheel, 15 aspindle on which is mounted the ratchet'wheel II and which is connectedby its lower end to a distributing valve 30 situated in the casing I!along the-line A -A oi I (Figure 5) of the device for operating thechange-speed gearing with which the gearchanging device is associated.The conduits 43 and 46 likewise lead to a cylinder (not shown)corresponding to the cylinder III.

The operation of the gear-changing devices shown in Figures 1 and 2 isas follows:

The various parts are in the positions shown in Figure 1 during normaltravelling, that is to say so long as no automatic gear-changing takesplace. The various teeth I to VI of the ratchet wheel I8 correspond to 6forward speeds. The gap between tooth VI and tooth I is left for thereverse speed and if desired for idling. The accelerator 3| has beenmoved by the driver so far from its stop 33 that by means of the rods33, 23, 26, 23 the throttle valve 25 has been adjusted to anintermediate position between idle running and full supply ofcombustible mix ture.

Assuming that the vehicle is travelling in the 4th gear, the tooth V ofthe ratchet wheel I3 will be in front of the pawl I3.

'Ihe centrifugal governor I is driven off a shaft connected withthedriving engine of the motor vehicle. So long as the speed of theengine is less than the maximum speed, the

centrifugal governor I and hence also the control valve 5 occupy theposition shown in the figure. The conduit 3 is connected to the outerair by the groove 6'. The tension of the spring 4 is so great that theforce, of the centrifugal governor I only exceeds it at maximum enginespeed. When the maximum engine speed is reached, the control valve 5 ismoved upwardly by the centrifugal governor to connect the compressed airsupply conduit 2 by the passage 5" with the conduit 8.

The pressure is transmitted through the conduit 3 to the piston II andmoves the latter to the right. The pawl I3 is thereby brought intoengagement with the ratchet wheel I6, and the latter is thereby rotatedby onetooth division, so that therefore the tooth V is brought into theposition of the tooth. IV. By this rotation (Figure 2) the spindle 35and the hand wheel 34 connected thereto as well as the valve 36,.

which previously were in the positions corresponding to the 4th gear,are rotated into the position corresponding to the 5th gear. Whereastherefore previously the conduit 42 leading to the cylinder III (Figure5) of the operating device of the "change-speed gearwas connected by thepassage 39 to the space above the valve 36 and hence to the compressedair supply conduit 33, the conduit 44 which likewise leads to saidcyliiider III and previously was connected to the outer air via therecess ,4I of the valve 36 and the hole 45, is now brought intocommunication with the space situated above the valve 36 and hencewiththecompressed air supply conduit 33, and simultaneously the conduit 42is connected to the outer air via the recess 4| of the valve 36 and. thehole 45. In the same way also the conduits 43 and 46 leading to anothercylinder (not shown) correspond ing to this cylinder IIIand controllinganother dog clutch may likewise be connected to the pressure mediumconduit 36 or to the outer air. The parts II2 to I22 shown in Figure 5are omitted when using the arrangement shown in Figure 1. These partsare-described. later with reference to Figure 3.

cylinder 3 situated on the left of the piston II.

The compressed air supplied thereby passes through the conduit I9 andenters the cylinder 20. The piston 2|, which occupies a positioncorresponding to the adjustment 01' the accelerator 3| by the driver, isthereby moved into its right-hand end position and acting through thepiston rod 22 'and the lever 23 brings the throttle valve 25 into theclosed or idle running position. The rod 26 is also shifted totherightand the spring 29 is compressed accordingly, but the accelerator 3| canbe held by the driver without difiiculty in the adjusted position. Inthis closed or idle running position of the throttle valve 25, the dogclutches I25, I26 heretofore in engagement are relieved of load, wherebyin consequence of the insertion of the fifth speed as describedhereinbefore, the compressed air in the conduit 44 becomes operativeand, upon the movement of the piston IIII from its left-hand endposition into its right-hand end position shown in Figure 5, brings thedog clutches I25, I26 out of engagement and the dog clutches I23, I24into engagement with one another.

The automatic gear-changing has thus been performed. In the meantime,the speed of the engine and hence that of the centrifugal governor 1will have diminished and the control valve 6 will have returned into itslower position. Due to the reduction in the pressure on the left of thepiston II and in the conduit 3 by the fact that these spaces are putinto communication with the outer air through the groove 6 (or evenmerely through leakage), the piston II will return to its left-hand endposition. The pawl I3 is thereby lifted off the ratchet wheel again andreturns into the position shown in Figure 1. The conduit I9 is againconnected by the groove I6 and the orifices I1 and I5 with the outerair, so that the piston 2| returns under the action of the spring 29into the position shown in Figure 1 and hence the throttle valve 25alsois again brought into the position set by the driver.

If at any time it is desired to make an optional gear change, either toa higher .or a lower speed, the handwheel 34 is simply rotated to bringthe valve 36 into the appropriate position and the change of gear isthen carried out by the gear changing cylinders.

In Figure 3 certain parts will be recognized as.

being similar to parts alreadydescribed in connection with Figure 1.These parts have been given the same reference numerals and it will notbe necessary to describe them again in detail.

In this embodiment the spring 4 of the centrifugal governor bearsagainst a disc 41 connected to a screw-threaded rod 43 which carries asmall handwheel 49 on its upper end. 63 is a valve under the pressure ofthe spring 64 and this valve comprises a. transverse pasage 65 and anangular passage 66. 61 is a further control valve which is under theaction of the spring 68 and likewise comprises a transverse passage 63,

In the casing I2 of this valve are also two an angular passage I0 and alongitudinal groove .II.

orifices I3 and I4, which are in communication 35 and a more accurateresponse obtagied with a conduit 81 is connected, the said pressuregovernor and valve or light and small, construction.. 82 is a casingaccommodating asiidablecontrol, valve 83 which comprise: an angularpassage 88 and is under the action of the spring 88. In the casing 82the communication with.

the compressed air supply conduit 88 is provided at 88, and at 81 is anorifice communicating with the outer air. The spring 88 bears with itsupper end against a piston 88 provided with a rod 88 carrying a knob 88on its upper end. 8| is the pressure chamber of the casing 82 to whichthe I space being situated below the valve 88.

Figure 4 is a cross-section along line BB of Figure 3 and like Figure 2,shows the control valve 88 and conduits connected thereto, the ratchetwheel I8 and the handwheel 88. In addition, this figure also shows avalve 82 which is mounted at thejunction of the conduits 88 and 88, isloaded by a spring 88 and possesses a transverse passage 88. Connectedto one end of the casing 88 of this valve 82 is a conduit 58.

- Figure 5 shows the operative parts or the change-speed gear 8| shownin Figure 3. In this gear, like the construction protected for theinventor by Re-issue 17,705 and by the U. S. Patents 1,949,167 and1,949,168, two dog clutches I28, I28

and I28, I28 are arranged between two pairs or gear wheels I88, IN andI82, I88 in' constant mesh, and on disengaging one of the dog clutches,the clutch members of the other dog clutch are brought without delay andwithout taking up any intermediate' position of rest, into yielding con:tact with one another. The end faces of the clutch dogs are bevelled sothat on this contacting oi the clutch members, the latter first alwaysrefuse each other until the first more rapidly rotating clutch memberbegins to become the slower member, whereupon final engagement takesplace. The gear whe I88 is'loose on the engine shaft I88, which carrieson its splin'ed portion I88 the slidable double dog sleeve I88. Thissleeve I88 in the left-hand end'position shown in the drawings connectsthe gear wheel I88 with theengine shaft I88, so that the drive takesplace through the gear wheels I88, |8|, I82 and I88 On a spindle I88 isa double-arm lever I88 con nected witha piston 8, the positions of thispiston II8 within its cylinder IIIconnected to the casing 81 (Figure 4)of the distributor valve 88 by-means of theconduits 82, 88, being de-.termined by the particular position of the valve 88. The double-armedlever I88 acts upon a con- 28 serving for retarding'the more rapidlyrunning trol valveI I8 slidabl'e in the casing. I I2 and having apassage II8 adapted to connect the conduit 88 supplyinsthe pressuremedium with the conduit 82 leading to the valve 88 (Figure 3) Inaddition, the control valve 8 has two angular passages H8 and II8 forcommunication with the outer air and the casing II2 has air escape boresII1and II8. Branching oi! the conduit 82 is a conduit I28 connected to acylinder II8, having its piston I2I connected to a brake device I22 dogclutch member. For cleamess the brake device I22 has been shownseparately in end view, though actually it is carried in the main clutchcasing or in the gearbox unit 8|;

The operation of the gear-changing device shown in Figures 3, 4and 5 issimilar to the constructional example'shown in Figures 1 and- 2. In thedevice according to Figure 3, however, the operation of accelerating iscarried out by means o! the device accommodated in the casing 82 withcompressed air transmission by the fact that, upon the knob 88 beinggradually depressed'by the driver, the spring 88 is compressed by theplunger 88, whereby an increasing pressure is exerted on the valve 88.The'iatter thereby moves downward a little irom the central positionshown and uncovers the compressed air supply conduit a little at theconnection 88, so that a certain quantity of compressed air canenter.The pressure in the chamber 8| is thereby increased suificiently toequalize the tension of the spring 88 adjusted by the driver, and inthis way the valve 88 is again returned to its central position. Uponthe knob 88 being released, the spring 88 is correspondingly relaxed,the valve 88 moves upward a little and allows some compressed air toescape at the mouth of the orifice 81,' so that the pressure in thechamber 8| falls until equilibrium is against established between thesaid pressure and the tension of the spring 88 adjusted by the driver..80

In this case also, the valve 88 immediately returns i to its centralposition. -I The pressure adjusted in the chamber 8| ,in

this way is transmitted through the conduit 81 and the transversepassage 88 of th valve 81, as 38 well as the conduit 88 to the cylinder28, and the -piston 2| in accordance with the adjusted presair entersthe conduit 8. This compressed air enters the chamber above the valve18. The latter is thereby moved into its lower end position andinsteadoi the pressure of the outer air previously transmitted through18, 8|, 88 and prevailing on the left of the piston II, compressed airnow passes from the conduit 82 through the passage 88 into the conduit88 and behind the piston II.

In the same way as was described with reference to Figure 1, the pawl I8will'now advance the wheel I8 by one'tooth. Towards the end of the.stroke or the piston II, insteadof the pres: sure of the outer airpreviously acting in the conduit I8 through I8, I1, I8, compressed airwill be supplied to the conduit I8 as soon as the lefthand edge ofpiston II has passed over the adso a mission opening 01 conduit I8 intothe cylinderO thereby connecting conduits 88 and I8 with one another.This compressed air passes through the passage 88 of the valve 88 andthe conduit 88 above the valve 81, which is thereby moved intoits lowerend position, in which the conduit 88 is connected to the orifice 18 bythe groove 1|; The compressed air contained in the cylinder 28 .isthereby released and the piston 2| :movesiinto its right-handendposition under the action of 79 the spring 18, whereby the throttlevalve 28 is ad- -Justcd to the idle-running position by the .rod 22 .andthelever 28;

Upon the downward movement of the valve 81, compressed air can first 12Mor a moment It pressed air moves the piston 2I somewhat to the left outof the idle-running position (right-hand end position), that is to saythe throttle valve is opened somewhat, thereby producing a change oftorque in the clutches of the change-speed gearing so that the gearspeed then in use is surely brought out of. action.

When the throttle valve 25 has been adjusted to a central position bythe driver in the manner described hereinbefore, the brief supply ofcompressed air through the passage III to the cylinder 26 during thedownward movement of the valve,6I will have little or no effect onwthesetting of the carburettor, since in any case there prevails in thecylinder 26 a certain air pressure which is not substantially altered bythe brief supply of compressed air.

As soon as the valve 61 is in its lower'position and the throttle valveis consequently closed, the speed of the engine falls., The controlvalve 5 again returns to its lower position and the supply of compressedair through the conduit 8 ceases. The latter 'is again connected to theouter air by the groove 6', the valve I6 again returns into its upperend position under the action of the spring 11 and connects the conduit54 once more with the outer air through the groove 8| and the orificeI9. The piston II thereby returns into its left-hand end position andthe conduit I9 is also connected to the outer air by I6, II, I5.

On the movement of the piston II into its right-hand position, the wheelI8 (Figure 3) as described hereinbefore is rotated forward by one toothby the ,pawl I3. The conduit 44 supplying the pressure medium to thecylinder III (Figure 5) is thereby disconnected by the distributor valve36 (Figure 4) from the source of pressure medium I or from the conduit38 and is connected to' the outer airthrough the recess 4| of the valve36, while on the other hand the conduit .42, heretofore connected to theouter air, is brought into communication with the conduit 38 supplyingthe pressure medium, so that the latter acts upon the piston I I0.Disengagement of the clutch is not possible, however, as long as theclutch members are still under load.

As soon as the throttle valve 25 has been closed in the mannerdescribed, by movement of the valve 61 into its lower position, and theclutch members I23. I24 in engagement are no longer under load, thelever I08 is rocked by the piston III], the clutch I23, I24 isdisengaged, the clutch members I25. I26 which refuse each other untilsynchonism is attained are brought to bear against each other and thecontrol valve H2 is moved to the left. The passage H4 is so'provided inthe control valve H3 that, in the refusal position of the clutch membersI25 and I26, it connects the pressure medium supply conduit 53 to theconduit 62 and compressed air is supplied to the right-hand end face ofthe valve 63 (Figure 3). The/said valve 63 is thereby forced into itsleft-hand end position and the 63 therefore prevents the aforesaidconnection of the conduit 55 with the compressed air acting behind thepiston II. On the contrary, as soon as the valve 63 has arrived in itsleft-handend position, the compressed air supplied from the conduit 62passes through the angular passage 66 to the conduit Hand in this wayforms a substitute for the compressed air previously sup plied from theconduit I9. The valve 61 is therefore still held in its lower endposition and the conduit 58 remains in communication with the atmospherethrough the groove II hnd the orifice I3 and the throttle valvetherefore remains closed.

The pressure medium supplied to the conduit 62 is now simultaneouslytransmitted through the conduit I20 (Figure 5) to the piston I2I, whichon yielding causes the brake device I22 to be operative and henceproduces a retardation of the more rapidly running clutch member. Bothclutch members will thereby have attained thesame speed in a relativelyshort time. Upon the previously more rapidly running clutch member beingovertaken by the previously more slowly running clutch member, the twodog clutch members I25 and I26 are brought into engagement by thepressure exerted by the piston H6 and the control valve II3'is broughtinto its left-hand end positioni. The conduit 53 is thereby closed, theconduits 62 and I20 are connected to the outer air and the brake deviceI22 is rendered inoperative. At the same time, the

valve 63 is returned into its right-hand end po-' sition under theaction of the spring 64. The conduit 55 is again connected by thepassage '65 to the conduit the piston II having moved to its'left-handend position, the compressed air above the valve 61 escapes and thevalve 61 returns again into its upper position. In this position,communication between the conduits 51 and 58 is established through thepassage 69. The piston 2I is thereby again put under the action of thepressure adjusted in the chamber 9| in-the above-mentioned manner by thedriver. The carburettor throttle is therefore again underthe optionalinfluence oithe driver.

The valve 82 shown in Figure 4 normally closes I9 and hence to the outerair.

the admission of compressed air from the conduit 59 to the conduit 38and hence to the distributor valve 86. As soonas gear-changing takesplace, that is to say, as soon as there is in. the conduit 55 compressedair first supplied through the control valve I6 and afterwards throughthe conduit 62, compressed air also acts through the conduit 56 on thevalve 82 so that the latter moves into its other end position and nowcompressed air-can also pass from the conduit 56 through the passage 95,the conduit 36 and the passages in the valve 86 to the geare changingcylinders. The latter thus only have compressed air supplied to themwhen this is necessary according to the previous adjustment ofthe-ratchet wheel I8 and hence of the disposition. In order thatgearchanging-may be effected optionally by hand, independently of theengine speed, a valve 38b is interposed in a conduit 38a leading fromthe compressed air container I to the distributing valve casing 31.

Said valve 38b is actuated byan operating pedal 38c and is adapted toallow compressed air to' pass into the distributing valve'casing 31 andthereby initiate the desired gear-changing operation.

By means of the handwheel 49, which if desired can be remote-controlled,the spindle 48. may be rotated in the screw-thread of the c'asing 3,'whereby the disc'41 is moved downwardly .or upwardly, so that thetension of the spring 4 isincreased or diminished, whereby thepredetermined engine speed at which the centrifugal governor 1 initiatesan upward movement of the control valve 5, is adiusted. j

Figure 6 shows diagrammatically a four speed gear with gear-changingcylinders and controlmeans. Figure 7 shows by way of example a plan ofan .arrangement of the air-passages for controlling the gear changingcylinders.

The geaiwheel pairs I21/I29, 'I'29/I39 and I3I/I32 are in constant mesh.The changing of the four different speeds is effected byv operation ofthe overtaking clutches I33, I34, I35 and I36 by the levers.l31 and I38.The wheel I21 is..f ast on the shaft I39 transmitting the drivingpower'.

The clutch I33 adapted to be coupled to the wheel I29 isslidable on oneside of said shaft I39. On the other side of wheel I29 is thedouble-sided clutch I35/ I36 which is slldable on the shaft I49 and isadapted to be coupled alternately .to the wheels I29 and I3I. The wheelI28 is fast on shaft I on which the clutch I34 is slidable.

Said clutch 134 is adapted to be coupled to the .wheel I39.- The wheelI39 is fast on shaft- 142, on

the other end of which the wheel I32 is likewise fast.

Gearchanging depends upon the position of the various clutches. Theclutches are operated by levers I31 and I38 which in their turn aredependent upon the pistons I45 and I46 movable in' cylinders 143 and m.The conduits m, m

open into the cylinder I43 and the conduits I49 and I59 into cylinderI44. Theposition of the pistons I45 and I46 and hence, throughlevers I31and I38, the position of the clutches I33, I34,

I35, I36will depend upon whether the .conduits are connected to thepressure medium or to the outer air. The conduits I41, I48, I49 and I59open intothe valve casing I5I. I52 is the pressure medium supply conduitand I53. is an airescape hole for connection with the outer air. At I54is a distributing valve moved by the spindle -155 over the inlets of theconduits I41 to I59.

The spindle I55 corresponds to spindle 35 and conduitl52 to conduit 38in Figures 1 to 4'. The distributingvalve I54 has through-way holes I56to I63 and bottomed holes I64 to I1I connected by special recesses I12to the air-escape aperture I53.

The spindle 1'55 moves the distributing valve I54 over the inlets of theconduits I. 41 to ,I59 (see also Figures 1 to 4) According to thevarious possible positions, which correspond to air in 'thevariousconduits I41 to I59, the pistons 445 and I46 in the cylinders I43 and(will be broughtto their right hand or left hand end positions, andthus, by'means of the levers I31, I38 the dog clutches-I33, I34, I35,I36 will be engaged or disengaged.-

Figure 7' shows the exact arrangment of the air passages. in thedistributing valve I54. In

gear-selecting, the series'of holes corresponding is in its right handend position.

According to.

to the various speeds and markedI to IV will be swung by the spindle I55in the plane A. B, and thereby the conduits I41 to I59 will be connectedin the correct sequence to the compressed air supply conduit or to theouter air.

Adjustment. for 1st speed The conduit I41 is connected to the outer, airby the bottomed hole I64 and aperture I53, the conduit I48 receivescompressed air through the through-way hole I56, the piston I46 movesinto its left hand end position, the clutch I33 is disengaged andclutchI34 is engaged. Conduit I49 is connected to the outer air by thebottomed hole I65 and conduit I59 is connected to the compressed airsupply by the through-way hole I51. The piston I46 is in its left handend posi tion, clutch I35 is disengaged and clutch I36 is engaged. i

Power transmission is through shaft I39, wheel I21,.wheel I29, clutchI34, wheel I39, shaft I42,

wheel I32,.wheel I3I,clutch I36, shaft I49.

- Adjustment for 2nd speed The .condult I41 receives compressed airthrough the through-wayhole I58; conduit I 49 islconnected to the outerair throughbmomed hole I66; The piston, I45, is in its right hand endposition. The clutch I33 is engaged and clutch I34 is disengaged.Conduit I49 is connected to the outer air through the bottomed hole I61,conduit I5 9 receives compressed air through the through-way hole I59.The piston I46 is in its left hand. end position. The clutch I35 isdisengaged and clutch -,I36 is engaged.

w Power transmission is through shaft I39, clutch I33, wheel I29,wheelll39, shaft I42, wheel.I32,'

wheel l3l, clutch I36, shaft I49.

Adjustment for 3rd speed The conduit I41 is connected to the outer airthrough the bottomed hole m, conduit a receives compressed air throughthe through-way hole I69. The piston I45 is in its left hand endposition. The clutch I33 is disengaged and clutch I34 is engaged. Theconduit I49 receives compressed air through the through-way hole I6I.The conduit I59 is connected to the .outer air through the bottomed.holeI69. The piston I46 The clutch I39 is engaged and clutch I36 isdisengaged.

Power transmission is through shaft I39, wheel I21, wheel I29, shaftI4I, clutch I34, wheel I39, wheel I29, clutch I35; shaft I49.

1 Adjustment for 4th speed {Shown in Figures 6 and 7) The conduit I41receives compressed airthrough the through-way hole I62." The conduitI43 is connected to the outer air through the bottomed l33,-wheel I29,clutch I35 direct to shaft I49 without any gearing-down taking placethrough the wheels [29, I39, I32, I3I or one ormore of them.

I claim:-- I 1. Change-speed mechanism for motor vehicles,

able means for moving said valve means toanydesired operative position,and pneumatically actuated means controlled by a device responsive toengine speed for movingsaid valve means from a lower speed position to ahigher speed position but not vice versa.

2. Change-speed mechanism claim 1, in, which the pneumatically actuatedmeans for actuating said valve means comprise a cylinder having a pistonconnected with a pawl,

said pawl co-operating with a ratchet-toothed- 'member to move saidvalve means in one direction only.

3. Change-speed mechanism as claimed' in claim 1, in which thepneumatically actuated means for actuating said valve means comprise acylinder having a piston, said piston also constituting a valve membercontrolling the supply of working fluid to other parts of the mechanism.

4. Change-speed mechanism as claimed in claim 1, including a controllingvalve between said valve means and a source of pneumatic power, meansassociated with the device responsive to engine speed for opening saidcontrolling valve at a predetermined engine speed, and means associatedwith said gear shifting means for holding said valve open until a changeof gear has been completed,

5. Change-speed mechanism as claimed in claim 1, including meansformoving the control member for the supply-oi fuel to the engine,pneumatically actuated means for closing said control member, and valvemeans for controlling the supply .of fluid pressure to saidpneumatically actuated means for closing said control member, adapted tobe moved by fluid pressure, the flow of fluid being controlled by enginespeed.

6. Change-speed mechanism as claimed in,

claim 1, including a pneumatically controlled valve between said valvemeansand a source of pneumatic power, means associated with the deviceresponsive to engine speed for supplying pressure fluid to open saidpneumatically controlled valve at a predetermined engine speed, and' asecond pneumaticaly controlled valve through which said fluid ressure'passes; and which is associated with said gear shifting means so as tobe closed by the fluid pressure operating therein, said second valvecomprising vmeans whereby said operating fluid pressure is then suppliedto said first pneumatically controlled valve to maintain the same open.J

'7. Change-speed mechanism as I claimed in claim 1, including a valvemechanically controlled by said speed responsive device and apneumatically, controlled valye controlling the supply of pressure fluidto said means for moving said gear-changing valve means, saidmechanically controlled valve controlling the supply of fluid pressureto said pneumatically controlled valve for controlling the latter.

8. Change-speed mechanism for motor vehicles, comprising a change-speedgear with toothed gear wheels giving alternative ratios,

power actuated gear-shifting means, means for controlling the'supply ofworking medium to said gear shifting means, means for manually actuatingsaid-controlling means so that any desired ratio may be brought intooperation, and means responsive to engine speed for actuating as claimedin said controlling means so that an upward gearchange is effectedautomatically upon a maximum engine speed being reached, said manualmeans alone being effective for changing to a lower ratio.

9. Change-speed mechanism as claimed in claim 8, including power'actuated means for throttling the engine fuel supply, said meanscooperating with the actuating means responsive to engine speed so thatthrottling takes place when said actuating means has moved said meanscontrolling the supply of working medium 'nearly to the end of itsmovement pertaining to the particular gear-changing operation beingeffected.

'10. Change-speed mechanism for motor vehicles, comprising achange-speed gear with toothed gear wheels giving alternative ratios,pneumatically actuated gear-shifting means, distributing valve means forcontrolling said gear-shifting means to bring any desired ratio intooperation, manually operable means for 'moving said distributing valvemeans to any desired operative position, pneumatically actuated meanscontrolled by a device responsive to engine speed for moving saiddistributing valve means from a lower speed position to a higher speedmission device between a manually operable member and a member forcontrolling the supply of fuel to the engine, and a valve in saidtransmission device whereby said fuel controlling member may be closedwhatever the position of said manually operable member, said valve beingoperatively connected to said pneumatically actuated means controlled inresponse to engine speed so as to be operated in conjunction therewith.

11. Change-speed mechanism for motor vehicles, comprising a change-speedgear of the kind comprising alternatively engaged dog clutches havingbevelled faces, pneumatically actuated gear-shifting means for engagingand disengaging said clutches to select diflerent gear ratios,distributing valve means for controlling said gear shifting means,manually operable means for moving said distributing valve means to anydesired operative position, pneumatically actuated means controlled by adevice responsive to engine speed for moving said distributing valvemeans from a lower speed position to a higher speed position but notvice versa, a fluid-pressureoperated retarding device operativelyconnected to said change-speed gear and to said pneumatically actuatedgear-shifting means so as to retardthe more rapidly rotating clutchmembers during the rejecting period of the dog clutches to be engaged, apneumatically controlled stop passes and which is connected to saidretarding device so as to be operated by the fluid pressure actingtherein to interruptrsuch passage when .said retarding device becomesoperative, said second valve comprising means whereby the fluid pressureacting in said retarding device is then supplied to said stop valve tomaintain the same open. 1

12. Change-speed mechanism for motor ve-v hicles, comprising achange-speed gear with toothed gear wheels giving. alternative ratios,pneumatically actuated gear-shifting means, distributing valve means forcontrolling said gearshifting means to bring any desired ratio intooperation, manually operable: means for moving said distributing valvemeans to any desired operative position, pneumatically actuated meanscontrolled by a device responsive to engine speed for moving saiddistributing valve means from a lower speed position to a higher speedposition.

but not vice versa, a pneumatic transmission device between a manuallyoperable member and a member for controlling the supply of fuel to theengine, and a pneumatically operated valve 'in towards its openposition.

said tron device whereby the pressure therein may be released to effectthe closing of such position is. admitted to said transmission 10 deviceto move said fuel controlling member KARL MAYBACH.

